Electromechanical sound recording and reproducing machine



Och 194s. J. H. REBOLD 2,330,919

ELECTROMECHANICAL SOUND RECORDING AND REPRdDUQING MACHINE Filed Feia. 25, 1941 3 Sheets-Sheet l INVENTOR J. H. REBOLD 7 Oct. 5, 1943'.

ELECTROMECHANICAL SOUND RECORDING AND REPRODUCING MACHINE Filed Feb. 25, 1941 3 Sheets-Sheet 2.

IN vzu TOR Oct. 5,1943. J. H REBOLD ELECTROMECHANICAL S OUND RECORDING AND REPRODUCING MACHINE Filed Feb. 25. 1941 5 Sheets-Sheet 3 FIG-.10 IZJ V AUDIOFREQ- 74 I AMPLIFIER O II/I/III/(l/II/IIIII/IA I F G. 5 F I 6'. l

a a 86 INVENTOR gers, arm rear-bearing, arm post, and stylus feed bar, when the arm is in its off position.

Fig. 5 is similar to Fig. 4, but shows the po sition of the various parts when the arm is in the playback position.

Fig. 6 is similar to Fig. 4, but shows the position of the various parts when the arm is about to leave the playback area and enter the neutral area.

Fig. '7 is similar to Fig. 4, but shows the posi tion of the various parts when the arm is at the start of the recording position, corresponde ing to the position indicated in ,Fig. 3.

Fig, 8 is a vertical sectional view taken upon line 8-'8 of Fig. 2, showing the arm in its off position. 7

Fig. 9 is a vertical sectional view taken upon line 9-9 of Fig. 3, and shows the front view of the arm in the recording position.

Fig. 10 is a schematic circuit diagram of the electrical connections between the various components.

Figs. 11 and 12ers enlarged views of the stylus in the playback and recording positions, respectively.

Figs. 13, 14, and 15 are enlarged views of the tip, front, and rear, respectively, of a suitable driven at suitable speed by any of the methods I well-known to the art, such as gear drive to the shaft, friction roller drive to the turntable rim, belt drive, etc.

Fastened to the baseboard I at a point outside the turntable 4 is a post 6, having ashoulder I abutting the top of baseboard I, and'a threaded lower portion ,8 cooperating with a lock nut 9 to lock post Bin a position substantially perpendicular to the baseboard I. Extending upward from the lower end of post 6 is an axial bore I3, and. communicating therewith is a transverse opening II, the combination, of the twoforming a passageway through which can be passed the leads from the recording-reproducing unit I2. At its upper end, the post 5 has a curved shoulder I3. and a short cylindrical projection I4, of reduced diameter rising therefrom, with a blind tapped hole centered therein adapted to receive the armretaining screw I5. Near its upper end post 6 has a transverse cutaway portion I6 allowing free entryof the tip of rear-bearing screw I'I when arm I8 isswung into recording position, as describedmore fully below. p

Arm I8 is formed with an elongated upper portion having a transverse cross-section of sub- 7 stantially an inverted U shape and near its front end carries the recording-reproducing unit I2, which is normally free to pivot in a vertical plane about the pivots l9 and 23, but is restrained from appreciable transverselmovement with respect to the arm I8 by the spacing washers 2| and 22. Near its front end. unit I2 carries the stylus chuck 23, into which is threaded'the stylus clamp-screw 24, which firmly clamps the stylus in substantially a perpendicular position. to

the long axis of recording-reproducing unit I2. Inside the front end of arm I3 is fastened the spring clip 26, whose function is to grip the shank of clamp-screw 24 when unit I2 is manually raised to its upper limit of travel, forming a releasable catch holding the stylus in an inactive elevated position when so desired.

The positions of pivots I9 and 23 are so chosen with respect to the center of gravity of recordingreproducing unit I2 that proper weight is placed on stylus 25 for recording purposes. In the present state of the recording art, using a record blank with a workable coating of cellulose nitrate or similar material from which a thread is to be cut by a sharp-edged stylus, the weight required upon'the stylus is in the neighborhood of two to three ounces. The weight of the recordingreproducing unit l2, being usually much greater than the required stylus weight, is arranged about the pivots I9 and 23 so that the greater portion is on the stylus side, and the difference between the two weight components is equivalentto the required stylus pressure. Substantially the same weight is applied to the stylus during the playback operation, two to three ounces having been found to be the optimum pressure for best groove tracking with a roundedpoint stylus.

The recording-reproducing unit I2 may be of any of the reversible function types of electromechanical transducers capable of either converting electrical undulations into corresponding mechanical Vibrations of the stylus, or of converting mechanical vibrations imparted to the stylus into corresponding electrical oscillations. Such convertible units are well-known to the art in both the piezo-electric and electo-magnetic types, and since the constructional details of the recordingereproducing unit are not included in my invention, such details are not shown.

The arm I 8 is provided near its rear end with a hollow, downwardly extending elbow 21, having at its lower end a fiat bearing portion 28 pierced -by a hole 29 of such size asto form an easy slide upwardly cupped portion 30 in substantially vertical alignment with hole 29 and adapted to rest upon the curved shoulder I3. A longitudinal slot 3! is cut in cupped portion 3!! of such dimensions as to form aslide fit about cylindrical projection I4. of post 6. The head of arm-retaining screw I5 is wider than slot 3|, so that when the arm It is placed in position to pivot about post 6, screw .I5 will prevent axial movement of the arm along the post.

Elbow 21 carries on its lowerfront side the downwardly extending legs 32 and 33, and the switch-tripping fingers 34 and 35 extending radially from post 8 as a center. Referring to Figs. 8 and 9, it is seen that leg 32 is longer than leg 33. Leg 32 is "made long enough so that it may always contact feed-bar 35 when arm I8 is swung into alignment with the feed-bar, even when the arm is raised vertically to the limit of its travel. Leg 33 is made short enough so that when arm I8 is raised vertically to its playback position, or higher, leg 33 Will clear feed-bar 35 vertically, but will contact the feed-bar when the arm is lowered to its recording position. The distance between legs 32 and 33 is made equal to the width of feed-bar 36, so that a close-fitting, re-

leasable coupling is. formed. when-arm I8 is. in recording position.

Switch-tripping, fingers 3A and 35. are arranged to. cooperate intermittently with slots. 31 and 3.8

in switch-plate 319 as. arm. l8 isv swung horizontal. ly into. its. various. operating positions,, and are formed with vertically. curved leading edges hav-. ing a vertical width'sufiicient so. that lifting. of arm 18; within. its normal limits. will. not. change their meshing. relation with the slots in switchpl-ate 38. Fingers 34 and 35 are mutually spaced ahorizontal. plane so that the angle formed. by the meeting. of their respective center lines at the vertical axis. of post ii is. substantially. equal to. the sum of. the. angles and P, representing, the off and playback areas respectively in Fig, 1..

The front wall of elbow 2i. is pierced by an. opening 41!, through. which may be. passed leads ll and 42 from unit. 12. The rear wall of elbow 27; near its. upper end carries the rear bearing screw l1, its axis parallel with the long axis of armv Ill, The. tip of screw l! is tapered. to a rounded point which cancooperate with the smooth peripheral surface of post. to form a. low-friction bearing tor horizontal rotation of arm l8 when it not in the recording position. When the tip of. screw ll leaves. the outer surfacev of postv it and enters the transverse cutaway portion Hi therein, as it. does. when arm L8 is.

swung. into recording position, the arm is automaically lowered by the force of gravity until the rear of slot. 3!. contacts the post projection. M

which then becomes the arm rear bearing- Feed-bar 3G is an. elongated member pivoted at one end about post fiforlimited. horizontal oscillation. between. the limits of the recording area R. This pivoted end. rests upon shoulder? of post 5, and is so. positioned with respect to the lower bearing portion 2.8 of elbow 2-! that when the arm I8. is in the recording position the lower side of portion 28 will contact the upper side oi feed-bar 35., while less 32 and: 3-3 contact the. opposite edges. Feed-bar 3% is. sloped downwardly irom its pivoted end. to. correspond with the slope of arm it when itis in its recording position, assuring a connection between the two when in this position,v yet allowing the arm to float freely upon its pivot, free ofany interference from the feed-bar when. the arm is raised toits playback position.

At its opposite end, teed-bar is linked with av throw. .It may be. mounted. withiits contact portion beneath. baseboard I. by. means ofnu't 4 8 coopexatingwith the threaded mounting' bushing. 4.9., which extendsthrough andabovebas'eboard as does also the switch control-shaft. 50.. Con

trol-shaft carries at its: upper endthebushimg it, to which. is. fastened. the. switch-plate 39,

l which latteris. provided with the radial slots. .31.

and 38; Slots 31. and 3tv are angularlyspaced; withrespect-tothe axis. of. control-shaft iafl by amount; equivalent to the angular displacement requiredof controleshaft fifi to. throwswitch 47 from a. given position to its next adjacent position, which angular displacement is usually thirtydegrees.. I

"The. vertical. axis. of switch. control-shaftiil is so located. with respect-toth-e vertical axis of post 5. that when arm. I8 is. in. its.- cit position as indicated in Figs. land fl, finger-35- rnesheswith slot 38 inswitch-plat e. ca. The horizontal: distance between the two. vertical axesis so chosen I that rotation. of arm L8. in; a counter-clockwise direction results in aclockwise, rotation or switchplate 39, and with it switch controlshaftcil, through just theanglerequiredtoth-row switch A? to its next adjoining position, after which further rotation of arm: la swi-ngs. finger 35 out of meshing relation with slot $8. leaving the arm free to move within playbackarea B. without afiecting the switch,

' The. electrical; contact portion of switch 4.1-

may consist. of the fixed insulating plate 52.;.'

carries the movable shorting contacts. 6.4, 6-5, and

6E, spaced ninety degrees apart adapted". to

short-circuit adjacent. pairs. of the fixed. circuit contacts.

Referrin to Fig. 10 ,v the audios frequency amplifier. 61 may be of the welil-lmown vacuum-- tubetype, having input terminals. i3 and 69', and. output terminals iii and H. may bee-f any well-known. type suitable for the purpose intended, its electrical input. terminals feed mechanism capable of moving the feed-bar slowly about its pivot and thus; feed stylus 25 radially across record 5- during the recording operation. A. suitable stylus feed mechanism is shown in my U. S. Patent No. 2.262299, issued Nov. ll.

1941, but other mechanisms known to the art may be used. In 2. is indicated a type of feed mechanism which is positioned between the turntable 4 and the baseboard i, and includes the feed head 4-3 containing the feed mechanism driven. by shaft 3 and operating to move rod (it! in.

a plane parallel with turntable At one end rod 44 is provided with a stop preventing further movement of arm it when it is swung. to the outer limit of the recording area. and at its opposite end carries,- the coupling yoke 4% coupling it with feed-bar 35-. When feed-bar 35 reaches a position corresponding to the inner limit of the being represented asv 1-3 'M. Terminals l5 and 15 represent a source of audio-irequency cur,

rent representative of sound to be recorded or amplified, such as a microphone,- radio receiver,

ietc. Low-potential terminals 42-, 68,. Hi, 13,.and" '15; oil unit l2, input and output of amplifier 61,,

loud-speaker 12, and the external source of audio-frequency currents, respectively, are all represented as being at ground potential for Ramiro-frequency currents.

High potentiai terminal M of' unit if! is electrically connected with switch terminal 5'4, Higlapotential terminal M of loud-speaker 12 is electrically connected with switch terminal 6%. High-potential input terj minal 6'9 of amplifier 67 isconnected with both of High-potential outswitch terminals 55 and 5?. put terminal ll of amplifier 51 is electrically connected with both of switch terminals ti) and 62. High-potential audio-frequency input terminal [5 is electrically connected with switch terminal 56.

Finally, switch terminals 53 and 59 are electrically connected together, while no connection is made to switch terminal 58. shorting contacts 64, and 55 are indicated in the intermediate or The loudspeaker 12 playback position, each being capable of moving one space in either direction to assume the rewith shaft 50 represent'the insulated mechanical connections between theseelements, and not an electrical connection.

Additional switching functions may be accomplished'by'adding additional stationary circuit terminals and movable shorting contacts to switch 41, in a manner well-known to the art, all under the automatic control of arm I8.

Referring to Figs. 11, 12, 13, 14 and 15, dualfunction stylus may be formed with an elon gated cylindrical body having at oneend a V- shaped that cutting face 'l'l ground substantially parallel to the stylus axis, the tip of the v being slightly rounded and the included face angle being made from eighty to, ninety degrees, to conform with standard recording practice. Converging rearwardly from each edge of cutting face 11 are the flat clearance faces 18 and 19, the merging of the three faces forming the sharp cutting tip 80, and giving this tip a triangular cross-section.

Intersecting the clearance faces I8 and 19, respectively, are the downwardly and inwardly converging rounded side faces 8| and 82, forming with the periphery of the cylindrical stylus body a V-shaped rounded tracking face 83, the included face angle of which may lie between twenty and sixty degrees, but in any case is smaller than the included face angle of cutting face Tl. Tracking tip 84 is rounded on all sides so as to result in minimum wear of the record groove during the playback operation, andis formed of such dimensions as to properly track the groove.

At the end opposite the tracking tip 84, and on the same side of stylus 25, is formed the fiat portion 85, adapted to cooperate with the tip of stylus clamp-screw 24 to firmly position stylus 25 in stylus-chuck 23, and assuring proper facing of the stylus with respect to the record. The axial length of stylus 25 from the tracking tip 84 to the top'end of the stylus is made slightly less than the axial length from the cutting tip 80 to the top end, so thatwhen the stylus is in its recording position, as indicated in Fig. 12, with the axis of stylus 25 close to vertical to record surface 5, tracking tip 84 will safely clear the record surfacewhile cutting tip 83 is cutting into the record 5.

The operation of my invention may best be understood by first assuming that arm I8 is in its off position clear of turntable 4, as indicated in Figs. 1, 2, 4, and 8. Unit I2 is supported in its raised inoperative position by the gripping acton of spring clip 26 upon clamp-screw 24.

rm I8 slopes upwardly from its pivot post 6, the weight of the arm being carried. by the rounded shoulder I3,*the tip of screw I1, and the front side of chamfered hole 29b Feed-bar 36 is in its inner rest position, feed mechanism 43 being held out of feeding relation therewith. Trip-finger is in meshing relation with slot 38 in switch-plate 39, and switch 41 is one position clockwise of the position indicated by the heavy lines of Fig. 10. Movable contacts-64 and 66 short-circuit terminals 55, 56, and GI, 62, re-

then be reproduced in amplified relation by loudspeaker 12.

To reproduce or playback a record, arm I8 is swung counter-clockwise until stylus 25 is over the starting groove in record 5 within playback area P. The arm has then assumed the position indicated in Fig. 5, trip-finger 35 having been swung out of meshing relation with slot 38 after shifting switch 41 one position to that indicated by the heavy lines in Fig. 10. Movable contacts 64, 65, and 66 now short-circuit terminals 5455, 5'I58, and GB'5I, respectively, thus connecting unit I2 to the input terminals of amplifier 61, while loud-speaker I2 is connected to the output terminals of amplifier El, and audio-frequency input terminals 15-16 are disconnected from operative'srelation with the amplifier. Mechanical vibrations of stylus 25 by cooperation with the record groove would thus result in a corresponding amplified sound reproduction by loudspeaker I2.

Arm I8 having been swung to playback starting position over record 5, unit I2 is manually released from control of clip 26 and lowered until tip 84 of stylus 25 contacts the record groove, the stylus then assuming the position indicated in Fig. 11, while unit I2 assumes the position indicated by the dotted lines in Fig. 2. By axially adjusting rear bearing screw I1, the vertical slope of arm I8, and in turn the vertical angle of stylus 25 in playback position, may be changed to conform with special conditions as required. When turntable 4 begins rotating in a clockwise direction, arm I8 is free to move horizontally within the playback area P solely under the control of stylus 25 cooperating with the record groove, without interference from switch-plate 39 or feed-bar 36, the latter remaining in its inner rest position during the playback operation.

When the reproducing or playback operation has been completed, arm I8 may then be swung clockwise and returned to its off position clear of the turntable. In so doing, trip-finger 35 again meshes with slot 38 from the opposite direction, restoring switch 41 to its first-described condition.

When it is desired to perform a recording operation, arm I8, assuming it is in off position, is again swung horizontally in a counter-clockwise direction, passing through areas 0, P, N, and R, until stylus 25 assumes a position over the rec- 'ord blank 5 near the outer limit of recording area R. In so doing, arm I8 acts as previously described until it reaches the position indicated in Fig. 6, corresponding to the junction of the playback and neutral areas, P and N, respectively. At this point trip-finger 34 is about to mesh with slot 31 in switch-plate 39, while the tip of rear bearing screw I1, which up to this point had been bearing against the periphery of post 6 and supporting arm I8 in an elevated position, is now about to enter transversecutaway portion I5 of post 6.

As the swing of arm I 8 continues across neutral area N and past the turntable spindle 3, the longer leg 32 of elbow 21 contacts the inner edge of feed-bar 36 as vertical alignment with the long axis of the latter is reached by the long axis of arm I8, so that during the remainder of the arm swing to the start of its recording position, feedbar 36 is carried along with it. The tip of screw I1 is now opposite the cutaway portion I5, of post 6, and no longer acts to support arm I8 in its elevated position.

Meanwhile, trip-finger 34 has left meshing re- 'lation with slot 31 in switch-platififl, after having moved switch '41 'toits remaining' positiomone step counter-clockwise of the position indicated by the heavy lines in Fig. 10. Movable contacts 64, -65, and '66 now short-circuit terminal pairs 5354, 56- 57, and' 59--60, respectively, thus connecting sound currentinput terminals 15-78 to input terminal-s '68-'69 oiamplifierfi'l, while terminals ib- 12 of unit l2 are connected'to output terminals :18'H of amplifier 61, speaker 12 being disconnected therefrom. Audio-frequency currents from a microphone, radio receiver, or other source, applied across terminals -'l5- 'Hi, would thus result in amplified mechanical-vibrations of stylus 25, carried by recording-reproducing unit When arm 18 has been completely swung around to the start of its recording position, it has assumed the position indicated in Figs. 3, '7,

andQiand in dotted'li-nes in-Fig. 1 the feed-bar 36 being unaligned position 'below it. The-weight of arm 18 "has caused 'it to assume a downward slope from its pivoted'en'd, the lower'bearing-por- 'tion 28 of elbow 27 now resting upon the upper surface of feed-bar -3'8, the opposite edges of which-are snugly embraced by both the longerleg I32 and the shorter leg33. The rear side of "slot 31 now contacts post extension 14, forming' the upperarmbearingabout postli.

The horizontal pivots I 9 and -20-of unit "l 2 "have :now Jbeen brought much-closer to the surface of record 5,.and when unit l 2 is released from Spring clip :26 and stylus 25 lowered onto-the record 5, cutting :tip L 80 is first -to contact the record surface, tracking tip 84 being held clear thereof, as

indicatedlFig. 12. 'l he direction-orrecord ro tation with respect to the stylus would'now be opposite :to that in the playback "position, since the -.stylus;is now onthe opposite side of the record spindle.

Feed-bar 35, having been brought away from its-inner .rest position, vis now under 'the control of .-feed Jnechanism 4'3, .and when turntable '4 starts rotating, moves slowly inward, carrying -=ar-m 1:8 andrstylust25 withit, :Inthis way cutting tm 80 'engraves l a spiral i or like' groove in: the surfaee o-f record5, the walls of'awhich arelmodulated'according to the soundzheing recorded in a manner welL-known to the art. a

:After the recording operation is completed,

stylus clamp screw 24 isrmanually :raised until gripped ;by;spring. clip:2 6,,:arm'il Bilifted until short 533 clears fed-bar'tifi,andzthezarm swung clock- Wise to. either the:playback or ioff positions. In so doing, :the .previouslynescrlbed conditions of switch position, arm r'bearing, :and arm slope are automaticallyrestored according to the horizontalipositionoi-armI 8. I I

Feed-bar 36,, having been :lelt in-some dntermediate position .in the recording area R upon completion of the irecordingxioperation, -=would continue ,;to feed inwardly :uponresumption-of turntable rotation subsequently for a :playback operation, until it reached'aitsiinner restposition, where it would automatically leave the control of feed mechanism 43. :I-Ioweverpif the subsequent operation is again-a: recording: operation, arm- [-8 through the long legu32 will-pick sup feed-bar tt no matter where the latter .is left mtherecording area R,: and carry itnutwardlyto the recordingstarting point. i r a To facilitate inspection :or changing of stylus :25 when required, arm 13 -:may be raised :higher than the positioniindicated in Fig; 2,'--to -a=poi-nt .wherezathe front :end of slot 3l '-strikes-"'the front side. of cylindrical projection I 4 atop postffi. This "may be done by the operator regardless of where the arm may happen to be, and will allow easy access to-thesty-lus. i I 1 From the foregoing description it will be seen .that'a system has been shown and described the manipulation :of auxiliary changes-over levers or other controls, aas required vwith previous ,sys-

.tems. The needyfor.closeattention andthe pos- .sibilities'; of .erroron the partor theopera n reduced to aminimu-m, permitting the systemt be successful yperatedrbyipersons with little-experience.

While I have thus .far des cribegd andshowmone form {of my invention, I;do ;not wish-to berestricted to ,thiswxaction Easrna-ny changes-are possi w thin-the scone. any; in tion w t ou e rt :f omthei neaq th -apne ed laims. .Seyeral such variations are ,indicated ;in ,Fig, 16.

.Here;the previouslydescribed,oVer-baseboardstyusr s d m chanism s-teen, replac d b t e feed-screw- .85, driven by ;a gear connection with the turntable shaft, .-and ,rotatably' mounted with .its ,axis'parallel with wandibelow baseboard l.

Feedebar ,36' now :has its pivot portion-above baseboard ,l, but. masses downwardly through opening, and continues in-aplane parallel to and below the baseboard, itsoppositeend ,carryinglthe .friction pad 8,8,adapted to cooperate with the feed-,screw,&6. ,Atits pivoted1end,-feed-bar ,fiii c'arries bushingltifl containingtheradialopen- ,i fl I o. .Arm --l8 now has its. upper wall [pierced hyfia chamfered I-hole ,cooperating with projection ll atop postlfi to form an uppers-armrbearingallowneif 'ee rotationoithe arm/in a-h0 1 zo taln1an and hunted :arm movement in ,a vertical plane. To allow such limited vertical arm movemeHE-el- .bow 2'1 {extending downwardly iron; the pivot end of arm 18 hasrits lower A 26 ;-pierced slot 31 t w n s ,fimabeut=i r ri err bushin 8. T ea e throu h tl ezlqwerm rtion of the front wall of elbow Z7 is thetaei bearing screw llf, its rounded; point cooperating th t e perinhery e hu hine u ismr ayback QntiQn and-W th pen] recording position. The comm 'y ira sed posi- {lion of the arm is indicated;by;=,the,qottednnesm .The .remainder. ,of .tl esystem and :the :moderor ously described.

a p sou d re ordin aria-reproducin nes 1 a b ;r cor turntable; easem- ,,ord;carriedrloy saidrt-urniiabie,anozrotatahle therewit @IBQQIQiIlg-l'fiDlDdllOlIlg.llnlll fl51191301131131- l'y i11g,aid ,unit. and movablam-a planer-substanp rati n ma be su stan iall thesamelaszprevily-,ilarallel .to that of said record -to a repro Ql1ClngrDOSLt10Il-100213601430 one side o1- --a drametric line passmgithrough thecentenof rotatlon ol s aid .IECOEda and lying in the planetoi its "i'ace and-to a :recording -position -locatedon the I opposite side of said diametric line, whereby-thedirection'or rotation of-saijdrecord, with respect to said unit,

is opposite in said recording position to that in i said reproducing position, a feed mechanism, and

means operatively connecting said support with said feed mechanism when said support is in said' recording position only.

2. In a disc sound recording, and reproducing machine, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith, a recording-reproducing unit, an arm pivot,

an arm carrying said unit and manually rotatto that in said reproducing position, a feed mechanismpand means operatively connecting said feed mechanism with said arm when said arm is in said recording position only. I

3. In a disc sound recording and reproducing machine, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith, an electro-mechanical recording-reproducing unit, an arm pivot located at a point outside of the perimeter of said record, an arm carrying said unit and manually rotatable about said pivot,-in a plane substantially parallel to that of said record, to a recording position located to one side of a line passing through the axes of rotation of both said arm and said record and to a reproducing position located on thejopposite side of said line with respect-to said recording position, a recording circuit, a reproducing circuit, a circuit switch controlling theelectrical connection of said unit with said recording circuit and said reproducing circuit, and means, controlled solely by the angular position of said arm about said pivot, to autcmaticallycondition said switch to connect said unit with-said recording circuit when said arm is in said recording position, and to connect aid unit with said reproducing circuit when said arm is in said reproducing position.

4. In a disc sound recording and reproducing machine, a rotatable record turntable; adisc record carried by said turntable and-rotatable therewith, an electro-mechanical recording-reproducing unit, an arm pivot located outside of' the periphery of saidrecord, an arm-carryingsaid unit and manually rotatable about said 'pivot, in

a plane substantially parallel to the plane of said 1 record, to arecording position located on'one side of a line passing through both the axisof rotation of said record and that of said arm,and to a reproducing position located on the opposite side of said line with respect to said recording position, a feed mechanism, a recording circuit, a reproducingcircuit, a circuit switch controlling the electrical connections of said unitwith'said recording and reproducing circuits, means operatively connectingsaid arm with said-feed mechanism when said arm is in said recording position, and means, controlled solelyby the angular position of said arm about said pivot, automatically conditioning said switch to connect saidunit with recording position, andto connect said unit with said reproducing circuit when said arm is in said reproducing position. r

5. In a disc sound recording and reproducing saidrecording circuitwhensaid arm isin. said machine, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith, a support manually movable in a plane ubstantially parallel to that of said record to a reproducing positionover one portion of said record and to a recording position over a different portion of said record,.a recording-reproducing unit pivotally mounted on said support and capable of vertical movement about a horizontal pivot axis, a stylus carried by said unit and adapted to operatively contact the face of said record in either of said positions, and means acting upon said support when in said reproducing position to cause said horizontal pivot axis to assume a predetermined vertically spaced relation with the face of said record, and a substantially difierent vertically spaced relation therewith when said support is in said recording position.

6. In a disc sound recording and reproducing machine, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith in a substantially horizontal plane, an arm pivot located outside of the periphery of said record, an arm manually movable about said pivot in a substantially horizontal plane to a recording position located to one side of a vertical plane passing through both said pivot and the axis of rotation of said record, and to a reproducing position located on the opposite side of said vertical plane from said recording position, a recordingreproducing unit pivotally mounted on said arm and capable of vertical movement about a hori- "zontal pivot axis, a stylus carried by said unit and adapted to operatively contact theface of said record in either of said positions, and means supporting said arm when in said recording position to cause said horizontal pivot axis to assume a predetermined vertically spaced relation with the face of said record, and a substantially different vertically spaced relation therewith when said arm is in said reproducing position, whereby said stylus assume a different vertical angle with the face of said record for each of said recording stylus-tip and a reproducing stylus-tip carried by said unit and adapted to alternately contact the face of said record, and means, controlled solely by the manual movement of said support to opposite sides of said spindle, causing the surface ofsaid record to be operatively contacted by the .saidrecording stylus tip when said support is in said recording position and by the said reproducing stylus tip. when said support is in said reproducing position.

8. In a sound recording and reproducing machine, a rotatable. record turntable, a disc record carried by said turntable and rotatable therewith in a substantially horizontal plane, an arm pivot located outside of the periphery of said record, a recording-reproducing. unit, an arm carrying said unit and manuallyfrotatable, in a substantially, horizontal plane about said pivot, to a reproducing position located to one side of a plane passing vertically through both said pivot recording position located on the opposite side of said vertical plane from said reproducing position, a reproducing stylus-tip and a recording stylus-tip carried by said unit and adapted to alternately contact the face of said record, and means controlled solely by the horizontal angular position of said arm about said arm pivot, to cause said reproducing stylus-tip to operatively contact the face of said record when said arm is in said reproducing position, and to cause said recording stylus-tip to operatively contact the face of said record when said arm is in said recording position.

' 9. In a sound recording and reproducing machine, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith in a substantially horizontal plane, a stylus having a recording face and an oppositely disposed reproducing face, a recording-reproducing unit carrying said stylus, and a support carrying said unit and movable, in a substantially horizontal plane, to a recording position located entirely to one side of a vertical plane passing through the axis of rotation of said record, and to a 'repro ducing position located entirely to the opposite side ofv said vertical plane from said recording position,'said support by its movement causing the recording face of said stylus to operatively engage the advancing face of said record during rotation thereof when said support is in said re- A cording position, and further causing the oppositely disposed reproducing face of said stylus to operatively engage the advancing face of said record when said support is in said reproducing position.

10. In a disc sound recording and reproducing apparatus, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith, an arm pivot located outside of the periphery of said turntable, an electro-mechanical recording-reproducing unit, an'elongated arm carrying said unit and manually rotatable about said pivot, in a plane subtsantially parallel to and above said record, to a reproducing position on one side of a plane passing through both the axes of rotation of said arm and said record, and to a recording position on the opposite side of said last-mentioned plane, a reproducing circuit, a recording circuit, a circuit switch controlling the electrical connections of said unit with said reproducing and recording circuits, and a trip member carried by said arm and adapted to automatically engage a complementary member carried by said switch as said arm is moved across said record, whereby said unit is connected with said reproducing circuit when said arm is in said reproducing position, and with said recording circuit when said arm is in said recording position.

11. In an electric sound recording and reproducing apparatus, the combination with a reversible recording-reproducing unit and a multiple position circuit control switch having a rotatable control shaft adapted to change the external electrical connections of said unit, of a tone-arm carrying said unit and rotatable about an axis spaced from and substantially parallel to that of said control shaft, a plurality of angularly spaced trip members carried by said tone-arm and extending radially from the axis of rotation thereof, and a plurality of angularly spaced complementary members carried by said control shaft and extending radially therefrom and adapted to engage intermittently with said trip members in meshing relation therewith as said tone-arm is 'tion in a horizontal plane and limited angular motion in a vertical plane, a set of horizontally spaced trip members ca'rried by said arm, and a corresponding set of complementary horizom tally spaced members carrie'dby the control member of said switch and adapted to engage intermittently with said trip members in meshing 'relation therewith assaid arm is manually rotated, at least one of said sets of members being extended in a vertical plane, whereby the horizontal rotationof said arm causes an intermittent movement 'of' the control member of said switch in predetermined relation therewith, regardless of the vertical angular-position of said arm within its limits of vertical movement.

13. In a disc sound recording andreprcducing apparatus, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith, an arm pivot located outside of the periphery of said turntable, an elec'tro-mechanica-1 recording reproducing unit, an arm carrying said unitand rotatable about said pivot, in a plane substantially parallel to and above said record, to a reproducing position located to one side or a plane passing through both the axes of rotation of said arm and of said record, and to a recording position locatedto the opposite side of said last-mentioned plane, a reproducing circuit, a recording circuit, a multiple position switch controlling the electrical connections of said unit with said reproducing and recording circuits and having a rotatable control shaft with its axis of rotation spaced from and substantially parallel to, said arm pivot, a plurality of angularly spaced trip members carried by said arm and extending radially from the axis of rotation thereof, and a plurality of 'angularly spaced complementary members carried by said control shaft and extending radially therefrom and adapted to mesh intermittently with said trip members as .said arm is rotated about its axis, whereby said 7 switch is automatically controlled to connect said,

unit with said reproducing circuit when said arm is in said reproducing position, and with said recordng circuit when said arm is in said recording position.

14. In a discsound recording and reproducing machine, a rotatable record turntable, adisc record carried by said turntable androtatable therewith, an arm pivot located outside of the periphery of said turntable, an arm manually rotatable about said pivot, in a plane substantlally parallel to and above that of said record, to a reproducing position located to one side of a line passing tnrough both the axes of rotation of said arm and said record, and to a recording position located to the opposite side of said line mom said reproducing position, a recording-reproducing unit carried by said arm, a feed-bar rotatable about a pivot in a plane substantially parallel to and below that of said record, a feed mechanism operatively connected to said feedbar and adaptedto cause slow rotation thereof about its pivot, and means operatively coupling said arm with said feed-bar when said arm is in said recording position only.

15. In a disc sound recording and reproducing machine, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith, a recording-reproducing unit, an arm pivot located outside of the periphery of said turntable, an arm carrying said unit and manually rotatable, in a plane substantially parallel to and above that of said record, to a reproducing position located to one side of a vertical plane,

passing through both the axes of rotation of said arm and said record, and to a recording 'posi-. tion located to the opposite side of said vertical plane from said reproducin p sition, a feedbar coaxially pivoted with said arm but normally detached therefrom and movable in a plane below said record, a feed mechanism operatively connected with said feed-bar and adapted to cause slow rotation thereof about its pivot, and releasable complementary coupling means carried by said arm and said feed-bar causing operative feeding engagement of said feed-bar with said arm when the latteris in said recording position, and releasing said feed-bar from operative engagement with said arm when the latter is in said reproducing position.

16; In a disc sound recording and reproducing machine, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith in a substantially horizontal plane, a recording-reproducing unit, an arm carrying said unit and rotatable about a pivot located outside of the periphery of said turntable, in a substantially horizontal plane, to a reproducing position located to one side of a vertical plane passing through both the axes of rotation of said arm and said record, and to a recording position 10- on the opposite side of said vertical plane, and means acting to displace at least a portion of said arm vertically with respect to said record surface as said arm passes from one of said positions, to the other, whereby said arm is supported in a predetermined vertically spaced relation with said record surface, when in said recording position, substantially difierent from that in said reproducing position.

ll. In a disc sound recording and reproducing machine, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith, an arm pivot located outside of the eriphery of said turntable, an arm rotatable about said pivot, in a plane substantially parallel to and above that of said record, to a recording position located to one side of a vertical plane passing through both the axes of rotation of said arm and said record, and to a reproducing position located on the opposite side of said vertical plane, a recording-reproducing unit carried by said arm, a stylus carried by said unit and adapted to operatively engage the surface of said record in either of said positions, a stylus feed mechanism, means releasably coupling said arm with said feed mechanism when said arm is in said recording position, and further means acting upon said arm to cause the axis of said stylus to assume a predetermined angular relation with the surface of said record when said arm is in said recording position, and to assume a substantially difierent angular relation with the surface of said record when said arm is in said reproducing position.

IS. In a disc sound recording and reproducing machine, a rotatable record turntable, a disc record carried by said turntable and rotatable therewith in a substantally horizontal plane, an arm pivotlocated outside of the periphery of said turntable, an arm rotatable about said Divot, in a plane substantially parallel to and above that of said record, to a reproducing position located to one side of a vertical plane passing through both of the axes of rotation of said arm and said record, and to a recording position located on the opposite side of said vertical plane from said reproducing position, a feed-bar coaxially pivoted with said arm and movable in a plane substantially parallel to and'below that of said record, a feed-mechanism operatively convnected with said feed-bar and adapted to impart a slow motion thereto about its pivot, a recording-reproducing unit movable about a substantially horizontal pivot carried by said arm, a stylus carried by said unit and adapted to operatively engage the surface of said record, means supporting said arm in a vertically spaced relation with the surface of said record when said arm is in said reproducing position and out of operative connection with said feed-bar, and means rendering said first-mentioned means inoperative when said arm is brought into said recording position and permitting said arm to be lowered into operative engagement with said feed-bar.

JACOB H. REBOLD. 

